Material sampling method and device

ABSTRACT

The present invention relates to a device and to a method for taking samples of a material such as a liquid, a viscous fluid, or a friable solid. Said device comprises a hollow &#34;sampling&#34; cylinder (10) defining an open cavity, said cavity co-operating with vent-forming means (34) and including inflatable shutter means (20) shaped so that, after said cavity has been filled with said material, they hold said material inside said cavity.

The present invention relates to a device for sampling a material and tothe method of taking samples of said material by using said device.

Said device and method of the invention are particularly suitable fortaking samples of a material such as a liquid--solution or suspension--aviscous fluid--sludges, for example--or a friable solid--a solid havingvery low hardness: sand or a hard solid that has previously beencrushed--.

At present:

solid samples are taken by using core-drilling equipment. Such toolsmainly comprise a hollow tube mounted at the end of a string of rods andhaving a sharp bottom edge;

to take samples of sludges, a core-drilling equipment is used initiallyto drill a sampling well, after which a pump is used to take the samplecontained in the well;

for sampling liquids, it is general to use syringes or pumps.

The present invention proposes an original device which is neverthelessunsuitable for taking samples of a material that is hard, as will easilybe seen by the person skilled in the art and reading the text below.Said device is particularly suitable for taking samples of sludges.

The device of the invention comprises a hollow "sampling cylinder" or"sample-taking" cylinder defining an open cavity, said cavityco-operating with vent-forming means and also including inflatableshutter means shaped, after said cavity has been filled with saidmaterial, to ensure that said material is held inside said cavity.

Once inserted into the mass of material to be sampled, said hollowcylinder is intended to fill, at least in part, with said material. Tothis end, at least one opening is provided, and the open cavity definedin this way co-operates with vent-forming means enabling the air (orpossibly some other gas initially present in said cavity) to be expelledby the material as the cavity fills with said material.

Said vent may be formed directly through one of the walls of the opencavity. It may also be provided in another part of a device that is morecomplex: said device including both the sampling cylinder and means forputting the inside of said cylinder (the sampling cavity) intocommunication with said vent.

The sampling cavity also includes inflatable shutter means suitable forshutting its opening(s) after it has filled, and for holding the sampledmaterial that has been trapped in this way inside the cavity. Said meansare retractable during positioning of the sampling device and while itis filling. They are connected to a device capable of applying pressurethereto in order to shut the opening(s) of the sampling cylinder and inorder to apply suction thereto to open said opening(s). Said inflatableshutter means advantageously comprise a rubber membrane that has beenthoroughly checked for strength and constant thickness. Said membranemust be capable of withstanding internal pressure suitable for closingthe cavity in sealed manner while it contains the sample that has beentaken.

The sampling cavity of the device of the invention is described aboveusing the term "hollow cylinder". This term is not limiting in any way.The person skilled in the art will easily understand that the teachingof the present invention is transposable to other embodiments and inparticular to cavities that are hemispherical, bell-shaped, . . . .Advantageously, the cavity of the sampling device of the invention is acircular cylinder.

Said sampling device of the invention may consist in the means describedabove: a sampling cylinder with one or more filling openings, a vent,and inflatable shutter means for the said opening(s) and connected to asource for feeding gas under pressure.

Advantageously, said means, which are essential, are associated withother means.

Thus, the device of the invention advantageously includes, in additionto the essential means described above, means for providing guideddisplacement of the sampling cylinder between a position in which theopening(s) of said cylinder is/are outside the material to be sampled,and a "sampling" position in which the opening(s) is/are in saidmaterial, and means for stopping said displacement and positioning saidcylinder in said sampling position.

For these purposes of guiding and positioning in the sampling position,it is possible to design numerous devices and in particular to useco-operation between at least one stud on the outside face of thesampling cylinder and a groove formed in a part external to saidcylinder. All such devices form an integral portion of the presentinvention.

The displacement and the positioning of said sampling cylinder whileempty, and also recovery thereof when full can be operations that areentirely manual, or else various mechanical means may be involved.

The invention is described below in greater detail with reference to oneof its preferred variants, in which variants:

said sampling cylinder is open at its bottom;

said inflatable shutter means are positioned in the vicinity of saidbottom; and

said sampling cylinder is mounted to be displaceable in verticaldownward translation inside another cylinder referred to as the "outer"cylinder which is likewise open at the bottom and which includes meansfor stopping and positioning said sampling cylinder in a low, samplingposition; said outer cylinder serving to guide said sampling cylinderduring such movement in translation.

Said sampling cylinder and said outer cylinder are organized for and/orinclude vent-forming means enabling the device to operate properly.

Guidance of said sampling cylinder inside said outer cylinder can beprovided in different variants using known means. In particular, over atleast a portion of their height, the outer face of said samplingcylinder and the inner face of said outer cylinder may include meansdesigned to co-operate and prevent any rotation of one of said cylindersrelative to the other. Said means may be of the type comprising alongitudinal groove and a stud.

To improve guidance of said sampling cylinder inside said outercylinder, it is also advantageously possible to provide at least one rodthat is secured at its top end to said outer cylinder and at its bottomend to a stationary piston. Said stationary piston constitutes stop andpositioning means for said sampling cylinder in its low, samplingposition, and is also advantageously of a size relative to the bottom ofsaid outer cylinder suitable, during downward translation movement ofsaid sampling cylinder to provide sealing for the pressure chamber thusdefined by said outer cylinder and said stationary piston, in whichpressure chamber said sampling cylinder moves in downward translation.

A plurality of rods may be provided. Advantageously, a single, centralrod is provided on the common axis of said sampling and outer cylinders.

The sampling cylinder is thus mounted inside a pressure chamber to bedisplaceable in translation inside the outer cylinder whose bottom is"shut" by the stationary piston. Naturally, said downward translationmovement of the sampling cylinder is possible only if the inside of saidsampling cavity or cylinder cooperates with vent-forming means. Such avent may be provided in the top wall of said sampling cylinder, therebyenabling excess pressure in the outer cylinder to be exhausted.

In another variant, which is preferred, the sampling cavity communicatesvia the rod with the outside. In this variant, said rod is hollow,including at least one orifice in its bottom portion in the vicinity ofthe stationary piston and opening out to the inside of the samplingcylinder, and connected at its top end to a vent level with the topportion or head of the outer cylinder. Thus, as the empty samplingcylinder moves downwards, the gas it initially contains is exhausted viasaid hollow rod. Said cylinder is stopped in its sampling position bythe stationary piston.

Advantageously, said stationary piston includes an electrical contact onits top face for the purpose of indicating that the sampling cylinder isin its low, sampling position.

In a preferred variant, said stationary piston is organized as follows:it comprises two portions that are united and a gasket that is heldhorizontal between them. Said gasket has two functions. Firstly itprovides sealing between the sampling cavity and the pressure chamberduring the downward translation movement of the sampling cylinder, andsecondly it acts during the downward movement of the outer cylinder oversaid sampling cylinder. During said downward movement of the outercylinder it acts as a scraper, thereby cleaning the inside walls of thesampling cylinder. When the device of the invention is used for taking asample of material, it is necessary to perform this step of moving thesaid outer cylinder downwards over the inner, sampling cylinder.

Such use comprises the following steps:

the sampling cylinder is initially engaged inside the outer cylinder;

said sampling cylinder is lowered until it comes into abutment againstthe stationary piston, for insertion into the material from which asample is to be taken;

said cylinder is filled with said material;

said cylinder is then shut at its bottom end by inflating the inflatableshutter means; the sample of material that has been taken is thustrapped inside the sampling cylinder in its low position;

said cylinder is then extracted from said material;

said cylinder, still in its low position in abutment against thestationary piston, is then emptied of the material it contains bydeflating said shutter means; the cylinder is then empty and in its lowposition; and

the said outer cylinder is then lowered over said sampling cylinder andsaid gasket performs its scraper function. The sampling cylinder is thenagain engaged inside said outer cylinder.

Taking a sample constitutes one cycle.

To lower the sampling cylinder into its low, sampling position provisionis made to inject a fluid under pressure into the top portion or head ofthe outer cylinder. Said fluid is intended to fill the pressure chamber.To this end, the top portion of said outer cylinder includes appropriateinjection means. Said top portion must also include means for exhaustingsaid fluid while the outer cylinder is moving down over said samplingcylinder in its low position. Advantageously, said top portion of theouter cylinder includes an opening to which a coupling can be fitted,which coupling is alternately connected to a source for feeding fluidunder pressure, and left open to the outside to constitute a vent. Thefluid under pressure that is used advantageously comprises a gas underpressure, such as compressed air.

To inflate the shutter means of the sampling cavity, it is alsonecessary to provide appropriate means. Said inflatable shutter meansadvantageously comprise a membrane able to generate a ring-shaped tube.As mentioned above, said membrane must have elasticity and strengthsuitable for performing its function. In order to shut the bottom of acircular cylinder, said membrane, when inflated, takes up the shape ofan annular and peripheral inner tube.

The means required for inflating and deflating said inflatable shuttermeans advantageously consist in connection means connecting saidinflatable shutter means to a source for feeding a fluid under pressure(for inflation) and enabling said fluid to travel in the oppositedirection (for deflation). Said connection means may consist, forexample, in a capillary tube and a hose; said capillary tube is situatedin the body of the sampling cylinder and connects said membrane to saidhose which is situated in the head of said outer cylinder; said hose isconnected to the source for feeding fluid under pressure (inflationfluid). Naturally, the length of said hose is adapted to the stroke ofthe sampling cylinder (between its high position inside the outercylinder and its low or sampling position). The fluid under pressurethat is used advantageously consists in a gas under pressure, such ascompressed air.

It is emphasized at this point that in the device of the invention theoperation of lowering the sampling cylinder to place it within thematerial, and the operation of inflating the inflatable shutter meansare totally independent. These two operations are implemented withdifferent means.

Advantageously, they make use of a gas such as compressed air. It ispreferable to use a gas rather than a liquid. The device is thus mademore independent and easier to manipulate.

In general, the device of the invention is very flexible in use. It isentirely suitable for taking contaminated and/or radioactive samples inan active cell.

While the outer cylinder is moving down over the sampling cylinder thathas been emptied of its contents, the stationary piston scrapes theinside walls of said sampling cylinder and thus performs a certainamount of cleaning. It will readily be understood that said cleaning ismade more effective if the piston is provided with a gasket, asmentioned above. Nevertheless, in order to improve said cleaning, it ispossible to provide for a cleaning fluid to be used, which fluid isadvantageously conveyed via the central rod. As mentioned above, saidrod is empty and provides communication between the inside of thesampling cavity and the outside via a vent which is provided on the topportion or head of the outer cylinder. It is possible to make provisionon said vent for receiving a cleaning liquid injector device to injectsaid liquid while the sampling cylinder is in its low position, and isempty, and while the outer cylinder is moving downwards. Said liquidtravels down along the hollow rod, passes through the orifice(s)provided in the bottom of said rod, and flows into an annular gapadvantageously formed in the top portion of the sampling cylinder. Saidliquid can be removed from the bottom because of the elasticity of thegasket held between the two portions of the piston.

Said gasket advantageously provides sealing while the sampling cylinderis being moved in downward translation, but does not provide sealingunder the pressure of the cleaning liquid while the outer cylinder isbeing moved in downward translation.

It is mentioned above that the outer cylinder moves down over the emptysampling cylinder. Nevertheless, it is perfectly possible for said outercylinder to begin its downwards movement and to continue it while saidsampling cylinder is emptying under gravity. The downwards movement ofsaid outer cylinder may assist in emptying out the sample through thebottom.

The device of the invention as described above includes a samplingcylinder whose bottom end is advantageously given a profile that isoptimized for the purpose of facilitating penetration into the materialfrom which a sample is to be taken. Said end is advantageouslychamfered.

The present invention also provides a method of taking samples of amaterial such as a liquid, a viscous fluid, or a friable solid; themethod is implemented using a device as described above. Said methodcomprises in particular:

inserting the sampling cylinder of the invention into said materialunder drive from a fluid injected into the pressure chamber defined bythe outer cylinder and the stationary piston, and until said samplingcylinder comes into abutment against the piston;

waiting for sufficient time to enable said material to fill saidsampling cylinder;

inflating the inflatable shutter means with a fluid under pressure inorder to hold said material trapped in said sampling cylinder;

extracting from said material said sampling cylinder containing saidsample of material;

deflating said inflatable shutter means to recover said sample ofmaterial; and

lowering the outer cylinder over said sampling cylinder.

Said sampled material is recovered when it flows out under gravity. Inthe preferred variant of the invention, said material may also be causedto flow within the device under drive from the stationary piston bydownward movement of the outer cylinder over the inner cylinder in itslow position.

The invention is described below with reference to the figuresaccompanying the present description.

FIGS. 1 to 4 show how the sampling method of the invention isimplemented.

FIG. 5 is a vertical section on V--V of a sampling device constituting apreferred variant of the invention.

FIG. 6 is a plan view of said device of the invention in section onVI--VI.

FIG. 7 is a view of said device in section on VI--VI.

FIG. 8 is a (half) section view of said device on VIII--VIII.

FIG. 9 is a (half) section view of said device on IX--IX.

In FIGS. 1 to 4, it can be seen that the device used essentiallycomprises a sampling cylinder 1 open at its bottom and provided in thevicinity of said bottom with an inflatable membrane 2 suitable, oninflation, for closing said bottom. Said sampling cylinder 1 isdisplaceable in translation inside an outer cylinder 3. In addition, itis guided during said translation by a central rod 4 that is secured atits bottom end to a stationary piston 5 and at its top end to the headof the outer cylinder 3.

Said device has a head constituted by a pressure chamber in which thesample-taking equipment or cylinder 1 moves in translation by aircompression. The vent-forming means are not shown in said FIGS. 1 to 4.

Said device is used as follows:

As shown in FIG. 1, it is brought over the location from which thesample of material M is to be taken.

Initially it is positioned with its bottom beneath the surface level ofthe material M to be sampled. While the inflatable membrane 2 isretracted, the sampling cylinder 1 then dives into and fills with saidmaterial M. The bottom edge of the sampling cylinder 1 is chamfered tofacilitate its penetration into said material M. The same applies to thebottom edge of said outer cylinder 3.

Once said sampling cylinder 1 is filled with said material M, saidmembrane 2 is inflated by being put under pressure using a suitablegas--e.g. nitrogen--so that it constitutes closure means for saidsampling cylinder 1 as filled with a sample of said material M. Saidclosure means are constituted by an annular tube whose inner wallpresses against itself.

In this way a determined quantity of said material M is enclosed in theinside volume of the sampling cylinder 1 (FIG. 2).

Sealing of said cylinder may be monitored by measuring the internalpressure of the annular tube.

Once the sample has been taken, the head is raised together with thefull sampling cylinder in its low position, and it is then placed over areceptacle or pot 6 for storage or subsequent analysis of the sample ofmaterial (FIG. 3).

The shutter--the inflated membrane 2--is then retracted by applyingsuction to the inside of the annular tube.

The sample of material M then runs out both under gravity and underdrive from the piston 5 due to the outer cylinder 3 being lowered overthe sampling cylinder 1 which is in abutment against the receptacle orpot 6. As it comes down, the piston 5 scrapes the inside walls of saidsampling cylinder 1, thereby "cleaning" them.

The device is then in the situation shown diagrammatically in FIG. 4.

FIGS. 5 to 9 show a preferred variant of the device of the invention ingreater detail.

In this variant, the sampling cylinder 10 is not a single piece. It ismade up of four portions referenced from top to bottom as follows: 10a,10b, 10c, and 10d. Said portions 10b and 10c constitute the samplingequipment proper. The top portion 10a is a moving piston secured to saidequipment 10b-10c by means of grub screw 11. The bottom portion 10d is achamfered block which serves firstly to facilitate penetration of saidsampling cylinder 10 into the material to be sampled, and secondly toco-operate in securing the bottom portion of the inflatable membrane 20.

The top portion of said inflatable membrane 20 is secured between 10band 10c.

Said sampling cylinder 10 is caused to move in vertical translationinside the outer cylinder 30. During this translation movement, it isguided by the central rod 40. Said central rod 40 is hollow and itsbottom end is secured by means of a screw 51 to a stationary piston 50.

Said stationary piston 50 includes a top portion 50a--a nut--and abottom portion 50b--a clamping washer--that are secured to each otherand that hold a gasket 52 between them. The gasket 52 is deformable.While the sampling cylinder 10 is moving downwards, it provides sealingbetween the cavity released for sampling and the pressure chamber 31 (bypreventing the material from gaining access to the space between the topof the piston 50a and the bottom of the portion 10a). While the cylinder30 is moving down over said cylinder 10, it cleans the inside wallsthereof by scraping them.

The top portion 50a of said stationary piston 50 includes a movingelectrical contact 53 mounted on a compression spring 54, said springaccommodating inaccuracies in the vertical positioning of the bottomportion of the moving piston 10a. Said contact 53 mounted in a housingthat is insulated from ground serves to provide ground continuity oncoming into contact with the base 55. Its purpose is to indicate thatthe sampling cylinder 10 is in its sampling position (its low position).Said position corresponds to said contact 53 coming into contact withthe top portion 10a of the sampling cylinder 10. Movement of saidcylinder 10 in translation inside the outer cylinder 30 is also guidedby co-operation between means 12 and 32 situated respectively in theoutside face of said cylinder 10 and the inside face of said cylinder30. Said means 12 comprise a longitudinal groove; said means 32 comprisea stud fixed by a screw; said stud 32 slides along said longitudinalgroove 12 during relative translation movement of one cylinder relativeto the other. Said means prevent any rotation between said cylinders 10and 30.

The inflatable membrane 20 is intended, on being inflated, to close thesampling cavity when the sampling cylinder 10 has been filled and is inits low position.

To this end, it is connected to a source that feeds it with fluid underpressure. The circuit for feeding said fluid comprises a coupling 21, ahose 22, and a capillary 23. Said hose 22 is wound helically thepressure chamber 31. It unwinds as the sampling cylinder 10 moves downto its low, sampling position.

To lower said sampling cylinder 10 into its sampling position, a fluidunder pressure is caused to act inside the pressure chamber 31. Saidfluid brought in from the outside via a duct 33 (FIG. 8). When the outercylinder 30 is moved down over said sampling cylinder 10 in its lowposition, said fluid must be capable of being removed. To this end, useis again made of the duct 33 which must open out to a vent.

As said sampling cylinder 10 is moving down into its sampling position,the air contained in the empty sampling cavity must be capable ofescaping. To this end, two orifices 41 are formed in the bottom portionof the hollow central rod 40 in the vicinity of the top portion 50a ofthe piston 50, and the top portion of said hollow central rod 40 isconnected to the outside. FIG. 9 shows that said air escapes to theoutside via a vent 34.

Finally, said hollow rod 40 is advantageously used to improve thecleaning of the inside walls of the sampling cylinder 10 by scraping bymeans of the gasket 52 while the outer cylinder 30 is moving down oversaid sampling cylinder 10 which is then empty and in its low position. Acleaning liquid is injected under pressure at 34 (to this end anappropriate injection device shown mounted on the vent orifice). Saidcleaning liquid travels along a rinsing circuit 36 which communicateswith said rod 40. Said liquid leaves via 41 to penetrate into an annulargap 13 provided in the top portion 10a of the sampling cylinder 10.Under the pressure of said liquid and given the relative movementbetween the two cylinders, the gasket 52 no longer provides sealing andthe cleaning liquid can be expelled downwards (the sampling cylinder 10being in its low position).

The operation of the device of the invention is briefly described belowwith reference to FIGS. 5 to 9.

Said device is put into contact with the substance from which a sampleis to be taken. The piston 50 is advantageously pushed into saidsubstance, at least in part. Fluid under pressure is injected into thechamber 31 via 33. Under drive from said fluid, the sampling cylinder 10moves downwards. Its downward travel is guided by the means 30, 40, 12,and 32. As it moves down, the air initially present in the samplingcavity escapes via 41, moves up along the hollow rod 40 and escapes tothe outside via the vent 34. As soon as said sampling cylinder touchesthe contact 53, fluid feed is interrupted. Said cylinder is then inabutment against the stationary piston 50.

Once the cylinder is filled with the substance to be sampled, themembrane 20 is inflated by injecting a fluid under pressure via 21.

The device as a whole--sampling cylinder in its low position and full ofsubstance--is then raised and put into position over a receptacle forthe sampled substance (see FIG. 3).

The membrane is then deflated by being subjected to suction. Thesampling cylinder thus discharges its contents. It is then to be foundempty and in its low position with the outer cylinder 30 above it. Saidouter cylinder 30 is then lowered over said empty cylinder 10. As itmoves down, a cleaning fluid is injected under pressure via 34 (to thisend, an appropriate injection device is mounted on the vent orifice).Said fluid circulates inside the hollow rod 40, escapes therefrom via41, circulates in the annular groove 13 and escapes downwards bydeformation of the gasket 52. It may be observed that said gasket 52provides sealing while the sampling cylinder 10 is moving downwards, butit no longer does so when the outer cylinder 30 is moving downwards.

During said downward movement of said outer cylinder 30 over thecylinder 10 in its low position, the pressure in the chamber 31 is inexcess. During this stage of the method, the coupling 33 opens out via avent.

It is specified below by way of non-limiting illustration that a deviceof the invention, as shown in FIGS. 5 to 9, may provide an effectivesampling volume of about 1 liter, and that it is entirely suitable forsampling sludges having viscosities lying in the range 1 centipoise to120 poises (viscosities measured with a Brookfield LVT viscosity meterfitted with a No. 2 disk rotating at 60 rpm (1983 model)).

Its essential components are made of stainless steel. The stationarypiston is made of bronze. The membrane constituting the inflatableshutter means is a rubber membrane obtained by molding. It is inflatedunder air or nitrogen pressure to a pressure lying in the range 1.2 barsto 2 bars. At such pressures, it is capable of retaining a liquid inliquid-tight manner.

To lower the sampling cylinder, compressed air or nitrogen is used. Theouter cylinder is moved down over the sampling cylinder while in its lowposition under manual drive.

We claim:
 1. A device for taking samples of a material comprising:ahollow sampling cylinder having an outer wall defining a cavity thereinand an open bottom communicating with said cavity; an outer cylinderhaving a top portion and an open bottom, said sampling cylinder beingmounted within said outer cylinder for movement relative thereto betweena first position in which said sampling cylinder is received within saidouter cylinder and a second position in which said sampling cylinder isdisplaced downwardly relative to said outer cylinder, said outercylinder guiding said sampling cylinder during relative movementtherebetween; a rod having a top end and a bottom end and beingconnected at its top end to said outer cylinder, said rod cooperatingwith said outer cylinder to guide said sampling cylinder; a stationarypiston secured to said bottom end of said rod, said piston stopping andpositioning said sampling cylinder in said second position; said outercylinder and said sampling cylinder defining therebetween a pressurechamber within which said sampling cylinder is displaced; inflatableshutter means positioned near said open bottom of said sampling cylinderand moveable between an inflated position wherein said inflatableshutter means shuts said open bottom of said sampling cylinder aftersaid cylinder has filled with said material thereby holding saidmaterial in said sampling cylinder, and a collapsed position whereinsaid inflatable shutter means does not close said open bottom of saidsampling cylinder; injecting means for injecting pressurized fluid intosaid pressure chamber for moving said sampling cylinder to said secondposition and for exhausting said pressurized fluid from said pressurechamber as said outer cylinder is moved downwardly over said samplingcylinder for returning said sampling cylinder to said first position;venting means for exhausting a gas contained within said sampling cavityas said sampling cylinder moves from said first position to said secondposition; said outer wall of said sampling cylinder having a conduittherein communicating at one end with said inflatable shutter means fortransmitting pressurized fluid to said inflatable shutter means formovement thereof to said inflated position and for suctioning saidpressurized fluid from said inflatable shutter means for movementthereof to said collapsed position; and a flexible hose in said pressurechamber connected at one end to a source of pressurized fluid and at theother end to said conduit for feeding pressurized fluid from said sourceto said inflatable shutter means.
 2. A sampling device according toclaim 1 wherein an outside face of said sampling cylinder and an insideface of said outer cylinder include, over at least a portion of theirheights, complementary cooperating means for preventing said cylindersfrom rotating relative to each other.
 3. A sampling device according toclaim 1, wherein said piston includes an electrical contact on its topface for indicating that said sampling cylinder is in said secondposition.
 4. A sampling device according to claim 1, wherein said pistoncomprises two united portions having a gasket therebetween, said gasketserving firstly as a seal between said sampling cavity and said pressurechamber during movement of said sampling cylinder to its second positionand secondly as a scraper during downwards movement of said outercylinder over said sampling cylinder as said sampling cylinder returnsto its first position.
 5. A sampling device according to claim 4,wherein said rod is hollow and connected at its top end to a liquidinjector device for injecting a cleaning liquid through said rod intothe empty sampling cylinder during the downward movement of said outercylinder thereon, said liquid passing out through at least one orificein said rod into an annular gap formed in the top portion of saidsampling cylinder, said cylinder being in said second position and saidliquid escaping during downward movement of said outer cylinder byvirtue of the resilience of said gasket held between said two portionsof said piston.
 6. A sampling device according to claim 1, wherein thebottom end of said sampling cylinder is configured to penetrate into thematerial to be sampled.
 7. A sampling device according to claim 1,wherein said rod is hollow for defining an axial bore therein and has atleast one orifice communicating said bore with said sampling cavity, andwherein said venting means communicates with the upper end of the axialbore, thereby providing a fluid path between said sampling cavity andsaid venting means.
 8. A sampling device according to claim 7, furthercomprising:a liquid feed source connected to said venting means forinjecting a cleaning liquid into said sampling cavity through saidorifice.
 9. The sampling device according to claim 1, wherein saidpressure chamber is defined at its lower end by said stationary pistonas said sampling cylinder moves to its second position.
 10. The samplingdevice according to claim 9, wherein said stationary piston includes agasket abutting the inside wall of the sampling cylinder for sealing thesampling cavity from the pressure chamber.
 11. A sampling deviceaccording to claim 1, wherein said inflatable shutter means comprises arubber membrane.
 12. A sampling device according to claim 1, whereinsaid flexible hose is helically wound about said rod.
 13. A samplingdevice according to claim 1, further comprising:a liquid feed sourceconnected to said venting means for injecting a cleaning liquid intosaid sampling cavity.
 14. A sampling device according to claim 1,wherein said rod is located centrally within said outer cylinder.
 15. Asampling device according to claim 6, wherein said bottom end of saidsampling device is chamfered.
 16. A sampling device according to claim1, wherein said stationary piston includes a circumferential sealingring dimensioned for close contact with the inside wall of the samplingcylinder at the bottom thereof below said inflatable shutter means forclosing the bottom of the sampling device when the sampling cylinder isin its first position, and a gasket above said sealing ring having anouter diameter greater than the outer diameter of the sealing ring forclose contact with the inflatable shutter means and the upper portion ofthe inside wall of the sampling cavity during relative movement of thesampling cylinder and outer cylinder, whereby said gasket seals thepressure chamber from the sampling cavity during downward movement ofthe sampling cavity to its second position and scrapes the inside wallof the sampling cylinder for cleaning same as said outer cylinder ismoved downwardly over said sampling cylinder for returning said samplingcylinder to said first position.
 17. A device for taking samples of amaterial comprising:a hollow sampling cylinder having an outer walldefining a cavity therein and an open bottom communicating with saidcavity; an outer cylinder having a top portion and an open bottom, saidsampling cylinder being mounted within said outer cylinder for movementrelative thereto between a first position in which said samplingcylinder is received within said outer cylinder and a second position inwhich said sampling cylinder is displaced downwardly relative to saidouter cylinder, said outer cylinder guiding said sampling cylinderduring relative movement therebetween; a rod having a top end and abottom end and being connected at its top end to said outer cylinder,said rod cooperating with said outer cylinder to guide said samplingcylinder; said outer cylinder and said sampling cylinder definingtherebetween a pressure chamber within which said sampling cylinder isdisplaced; inflatable shutter means positioned near said open bottom ofsaid sampling cylinder and moveable between an inflated position whereinsaid inflatable shutter means shuts said open bottom of said samplingcylinder after said cylinder has filled with said material therebyholding said material in said sampling cylinder, and a collapsedposition wherein said inflatable shutter means does not close said openbottom of said sampling cylinder; a stationary piston secured to saidbottom end of said rod, said stationary piston including acircumferential sealing ring dimensioned for close contact with theinside wall of the sampling cylinder at the bottom thereof below saidinflatable shutter means for closing the bottom of the sampling devicewhen the sampling cylinder is in its first position, and a gasket abovesaid sealing ring and having an outer diameter greater than the outerdiameter of the sealing ring for close contact with the inflatableshutter means and an upper portion of an inside wall of the samplingcavity during relative movement of the sampling cylinder and outercylinder, whereby the gasket seals the pressure chamber from thesampling cavity during downward movement of the sampling cylinder to itssecond position and scrapes the inside wall of the sampling cylinder forcleaning same as said outer cylinder is moved downwardly over saidsampling cylinder for returning said sampling cylinder to its firstposition, said piston stopping and positioning said sampling cylinder insaid second position; injecting means for injecting pressurized fluidinto said pressure chamber for moving said sampling cylinder to saidsecond position and for exhausting said pressurized fluid from saidpressure chamber as said outer cylinder is moved downwardly over saidsampling cylinder for returning said sampling cylinder to said firstposition; venting means for exhausting a gas contained within saidsampling cavity as said sampling cylinder moves from said first positionto said second position; said outer wall of said sampling cylinderhaving a conduit therein communicating at one end with said inflatableshutter means for transmitting pressurized fluid to said inflatableshutter means for movement thereof to said inflated position and forsuctioning said pressurized fluid from said inflatable shutter means formovement thereof to said collapsed position; and a flexible hose in thepressure chamber connected at one end to a source of pressurized fluidand at the other end to said conduit for feeding pressurized fluid fromsaid source to said inflatable shutter means.
 18. A device for takingsamples of a material comprising:a hollow sampling cylinder having anouter wall defining a cavity therein and an open bottom communicatingwith said cavity; an outer cylinder having a top portion and an openbottom, said sampling cylinder being mounted within said outer cylinderfor movement relative thereto between a first position in which saidsampling cylinder is received within said outer cylinder and a secondposition in which said sampling cylinder is displaced downwardlyrelative to said outer cylinder, said outer cylinder guiding saidsampling cylinder during relative movement therebetween; venting meansfor exhausting a gas contained within said sampling cavity as saidsampling cylinder moves from said first position to said secondposition; a hollow rod having a top end and a bottom end and beingconnected at its top end to said outer cylinder, said rod cooperatingwith said outer cylinder to guide said sampling cylinder during relativemovement between said sampling cylinder and said outer cylinder, saidrod defining an axial bore therein and having at least one orificecommunicating said bore with said sampling cavity, and wherein saidventing means communicates with the upper end of the axial bore, therebyproviding a fluid path between said sampling cavity and said ventingmeans, said upper end of said axial bore also being connected to aliquid injector device for injecting a cleaning liquid into the emptysampling cylinder through said orifice when said sampling cylinder is insaid second position and during downward movement of said outer cylinderthereon, said liquid filling an annular gap formed between a top portionof said sampling cylinder and said rod; said outer cylinder and saidsampling cylinder defining therebetween a pressure chamber within whichsaid sampling cylinder is displaced; inflatable shutter means positionednear said open bottom of said sampling cylinder and moveable between aninflated position wherein said inflatable shutter means shuts said openbottom of said sampling cylinder after said cylinder has filled withsaid material thereby holding said material in said sampling cylinder,and a collapsed position wherein said inflatable shutter means does notclose said open bottom of said sampling cylinder; a stationary pistonsecured to said bottom end of said rod, said stationary piston includinga circumferential sealing ring dimensioned for close contact with theinside wall of the sampling cylinder at the bottom thereof below saidinflatable shutter means for closing the bottom of the sampling devicewhen the sampling cylinder is in its first position, and a gasket abovesaid sealing ring and having an outer diameter greater than the outerdiameter of the sealing ring for close contact with the inflatableshutter means and an upper portion of an inside wall of the samplingcavity during relative movement of the sampling cylinder and outercylinder, whereby the gasket seals the pressure chamber from thesampling cavity during downward movement of the sampling cylinder to itssecond position and scrapes the inside wall of the sampling cylinder forcleaning same as said outer cylinder is moved downwardly over saidsampling cylinder for returning said sampling cylinder to its firstposition, said piston stopping and positioning said sampling cylinder insaid second position; injecting means for injecting pressurized fluidinto said pressure chamber for moving said sampling cylinder to saidsecond position and for exhausting said pressurized fluid from saidpressure chamber as said outer cylinder is moved downwardly over saidsampling cylinder for returning said sampling cylinder to said firstposition; said outer wall of said sampling cylinder having a conduittherein communicating at one end with said inflatable shutter means fortransmitting pressurized fluid to said inflatable shutter means formovement thereof to said inflated position and for suctioning saidpressurized fluid from said inflatable shutter means for movementthereof to said collapsed position; and a flexible hose in the pressurechamber connected at one end to a source of pressurized fluid and at theother end to said conduit for feeding pressurized fluid from said sourceto said inflatable shutter means.